docs: def ls(manager: Manager, url: Optional[str], namespace_id: Optional[int]):
      """List cached namespaces."""
      if url:
          n = manager.get_or_create_namespace(url)
          if isinstance(n, Namespace):
              _page(n.entries)
          else:
              click.echo('uncachable namespace')
      elif namespace_id is not None:
          _ls(manager, Namespace, namespace_id)
      else:
          click.echo('Missing argument -i or -u')